Are you getting the most out of your sunscreen?
Posted on 3 December 2018
Dr Karen Ordemann, a dermatologist at Mediclinic Milnerton, explains the importance of sunscreen and points out the ways you’ve been using it incorrectly.
How do I choose the sunblock that’s right for me?
Dr Ordemann: It depends on your skin colour. Look at the sun protection factor (SPF) label on the product. That tells you how long it takes for your skin to burn when you’re wearing it, compared to how long it takes without it. The higher the SPF number, the better the protection.*
If you’re fair-skinned, always go for factor 50. The thing is, that’s what you get under perfect circumstances, in lab conditions. But to get that level of protection, you have to apply a thick layer, every couple of hours. In real life you’re not getting a 50 because you’re probably not applying enough – nobody does. So if you start with a 50, in practice you end up with far less.
Even if you’ve got very dark skin, choose at least a 15 for protection and even skin tone.
Next, look for the type of light rays the sunscreen protects against. Most sunscreens cover UVB rays or at least most of that spectrum. They don’t all cover UVA (penetrates deep into the dermis, the skin’s thickest layer), or they don’t do it very well. So go for a reputable, well-known brand that says it covers both UVA and UVB.
If you’re exercising and perspiring, or swimming and towelling yourself dry, choose a sports sunscreen as it will stay on your skin longer.
INFOGRAPHIC: 10 things you need to protect yourself, and your family, from the sun [Internal link to December content]
Do I apply sunscreen over my moisturiser?
Dr Ordemann: Apply it before you apply any moisturiser. And put on a proper layer.
How much sunscreen should I apply?
Dr Ordemann: A CANSA article says sunscreen manufacturers globally have agreed that the thickness of application should be 2mg per square centimetre of skin, which means that an adult in a swimming costume would use about a third of a bottle of sunscreen! We don’t use nearly as much as we should.
What areas are most often neglected?
Dr Ordemann: People neglect the area behind their ears, the back of the neck, and the creases around the nose, so make sure you cover those too! We see a lot of skin cancers [Internal link: https://www.mediclinicinfohub.co.za/skin-cancer/] in those areas, especially in men.
When should I apply sunscreen?
Dr Ordemann: Most sunscreens have a physical and a chemical block in them. The physical block, a substance like zinc oxide that absorbs or reflects ultraviolet radiation, works immediately. That’s the cream you see the cricketers wearing, though there are also formulations containing zinc oxide that are not visible on the skin. The chemical blocker needs to be absorbed before it starts working, which is why you’ll read the instruction on the bottle to apply the sunscreen at least half an hour before you go into the sun. And you do need to reapply it.
How often should I apply sunscreen?
Dr Ordemann: If your skin is very fair and your risk of skin cancer and pigmentation is high, use sunscreen every single day. But if you’re born with the better protection of a darker skin, and you’re indoors, you don’t need to put it on daily in winter.
*If your skin normally begins to burn after 10 minutes in full sun without any protection, a 30 SPF sunscreen would provide 30 times more protection than no sunscreen. In other words, it will take 30 times longer (300 minutes) before you start to burn.